Thermoplastic blend

ABSTRACT

The invention generally relates to thermoplastic blends having improved properties. Optionally, these blends may be dynamically vulcanized. More specifically, this invention is directed to a composition comprising a blend of chloromethylated(styrene-isobutylene) polymer and a thermoplastic resin selected from the group consisting of polyamides, polyesters, polycarbonates, polysulfones, polyacetals, polyacetones, acrylonitrile-butadiene styrene resins, polyphenylene oxide, polyphenylene sulfide, styrene-acrylonitrile resins, styrene-maleic anhydride resins, polyamides, aromatic polyketones, ethylene vinyl alcohol polymer and mixtures thereof. Tires and tire components such as air permeation prevention films comprising these compositions are also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Ser. No. 09/594,650, filedJun. 15, 2000, now U.S. Pat. No. 6,376,598, herein incorporated byreference in its entirety.

FIELD

[0002] The invention relates to thermoplastic blends having improvedproperties. Optionally, these blends may be dynamically vulcanized.

BACKGROUND

[0003] Significant research has been conducted in an effort to findpolymer blends which have a combination of both elastic andthermoplastic properties. These polymer blends have been given thegeneric designation of Thermoplastic Olefins (“TPO”). They exhibit someof the properties of a cured elastomer as well as the reprocessabilityof thermoplastic resins. The elastomeric characteristics may be enhancedif one component of the blend is a vulcanizable elastomer which iswholly or partially crosslinked.

[0004] The earliest work in the curing of TPO compositions was byGessler and Haslett in U.S. Pat. No. 3,037,954. That patent teaches theconcept of “dynamic curing” wherein a vulcanizable elastomer isdispersed into a resinous thermoplastic polymer and the elastomer curedwhile continuously mixing and shearing the polymer blend. The result isa micro-gel dispersion of cured rubber in an uncured matrix of resinousthermoplastic polymer. Gessler's U.S. Pat. No. 3,037,954 disclosescompositions comprising polypropylene and a rubber wherein the rubbermay be butyl rubber, chlorinated butyl rubber, polybutadiene,polychloroprene and polyisobutylene. Compositions of 50 to 95 partspolypropylene and 5 to 50 parts of rubber are disclosed.

[0005] Dynamically vulcanized thermoplastic compositions comprising apolyamide and various types of elastomers are known. See, for example,U.S. Pat. No. 4,173,556; U.S. Pat. No. 4,197,379; U.S. Pat. No.4,207,404; U.S. Pat. No. 4,297,453; U.S. Pat. No. 4,338,413; U.S. Pat.No. 4,348,502; U.S. Pat. No. 4,419,499, and U.S. Pat. No. 6,028,147.Specifically, U.S. Pat. No. 6,028,147 to Ogawa et al. discloses atriblock polymer including methylstyrene and p-(chloromethyl)styrene.Also, EP 0 542 875 to Dharmarajan et al discloses a polymer having halopara-methylstyrene derived unit within the polymer. None of thesedisclosures discloses a polymer having both meta and para-halogenatedmethylstyrenes and having improved durability and lower airpermeability.

SUMMARY

[0006] It has now been found that compositions comprising athermoplastic resin and chloromethylated(styrene-isobutylene) randompolymer or “tetramer” that includes styrene-derived units,p-(chloromethyl)styrene derived units, and m-(chloromethyl)styrenederived units have improved properties which make them particularlyuseful in the manufacture of tires in thermoplastic blends. Thecompositions may also comprise uncured or dynamically cured elastomers.

[0007] Thus, the present invention is directed generally to acomposition comprising a blend of chloromethylated(styrene-isobutylene)tetramer and a thermoplastic resin selected from the group consisting ofpolyamides, polyesters, polycarbonates, polysulfones, polyacetals,polyacetones, acrylonitrile-butadiene styrene resins, polyphenyleneoxide, polyphenylene sulfide, styrene-acrylonitrile resins,styrene-maleic anhydride resins, polyamides, aromatic polyketones,ethylene vinyl alcohol polymer and mixtures thereof. Tires and tirecomponents such as air permeation prevention films comprising thesecompositions are also provided.

DESCRIPTION

[0008] The thermoplastic compositions of the present invention comprisea blend of a thermoplastic resin and achloromethylated(styrene-isobutylene) polymer. The blend may be anunvulcanized composition or may be statically vulcanized or subjected todynamic vulcanization.

[0009] The term “dynamic vulcanization” is used herein to mean avulcanization process in which the resin andchloromethylated(styrene-isobutylene) polymer are vulcanized underconditions of high shear. As a result, the vulcanizable elastomer issimultaneously crosslinked and dispersed as fine particles of a “microgel” within the resin matrix.

[0010] Dynamic vulcanization is effected by mixing the resin andchloromethylated(styrene-isobutylene) polymer at a temperature which isat or above the curing temperature of the polymer in equipment toprovide high shear such as roll mills, Banbury™ mixers, continuousmixers, kneaders or mixing extruders, e.g., twin screw extruders. Oneunique characteristic of the dynamically cured compositions is that,notwithstanding the fact that the polymer component may be fully cured,the compositions can be processed and reprocessed by conventional rubberprocessing techniques such as extrusion, injection molding, compressionmolding, etc. Scrap or flashing can be salvaged and reprocessed.

[0011] The thermoplastic resins suitable for practice of the presentinvention may be used singly or in combination and are resins containingnitrogen, oxygen, halogen, sulfur or other groups capable of interactingwith an aromatic haloalkyl group. Suitable resins include resinsselected from the group consisting of polyamides, polycarbonates,polyesters, polysulfones, polylactones, polyacetals,acrylonitrile-butadiene-styrene resins (ABS), polyphenyleneoxide (PPO),polyphenylene sulfide (PPS), styrene-acrylonitrile resins (SAN),polyimides, styrene maleic anhydride (SMA), aromatic polyketones (PEEK,PEK, and PEKK), ethylene vinyl alcohol polymer and mixtures thereof.Preferred thermoplastic resins are polyamides. The more preferredpolyamides are Nylon 6 and Nylon 11.

[0012] Suitable thermoplastic polyamides (nylons) comprise crystallineor resinous, high molecular weight solid polymers including polymers andterpolymers having recurring amide units within the polymer chain.Polyamides may be prepared by polymerization of one or more epsilonlactams such as caprolactam, pyrrolidione, lauryllactam andaminoundecanoic lactam, or amino acid, or by condensation of dibasicacids and diamines. Both fiber-forming and molding grade nylons aresuitable. Examples of such polyamides are polycaprolactam (Nylon-6),polylauryllactam (Nylon-12), polyhexamethyleneadipamide (Nylon-6,6),poly-hexamethyleneazelamide (Nylon-6,9), polyhexamethylenesebacamide(Nylon-6,10), polyhexamethyleneisophthalamide (Nylon-6,IP) and thecondensation product of 11-amino-undecanoic acid (Nylon-11). Nylon 6(N6), Nylon 11 (N11), Nylon 12 (N12), a Nylon 6/66 polymer (N6/66),Nylon 610(N610), and Nylon 612 (N612) may also be used.

[0013] Additional examples of satisfactory polyamides (especially thosehaving a softening point below 275° C.) are described in 16 ENCYCLOPEDIAOF CHEMICAL TECHNOLOGY 1-105 (John Wiley & Sons 1968), CONCISEENCYCLOPEDIA OF POLYMER SCIENCE AND ENGINEERING 748-761 (John Wiley &Sons, 1990), and 10 ENCYCLOPEDIA OF POLYMER SCIENCE AND TECHNOLOGY392-414 (John Wiley & Sons 1969). Commercially available thermoplasticpolyamides may be advantageously used in the practice of this invention,with linear crystalline polyamides having a softening point or meltingpoint between 1600-170° C. being preferred.

[0014] Suitable thermoplastic polyesters are those that are linear,crystalline and have high molecular weight. The term “linear” as usedherein in respect to polyester means a polymer in which the recurringester groups are within the polymer backbone and not pendant therefrom.Linear crystalline polyesters having a softening point above 50° C. aresatisfactory, with polyesters having a softening point or melting pointabove 100° C. being preferred, with polyesters having a softening pointor melting point between 160° C. to 260° C. being more preferred.Saturated linear polyesters (free of olefinic unsaturation) arepreferred, however, unsaturated polyesters may be used provided that therubber, if cross-linked, is cross-linked prior to blending with thepolyester or provided that the rubber is dynamically cross-linked with across-linking agent that will not significantly induce cross-linkformation in the polyester.

[0015] Many commercially available thermoplastic linear crystallinepolyesters may be advantageously employed in the practice of theinvention or they may be prepared by polymerization of one or moredicarboxylic acids, anhydrides or esters and one or more diol. Examplesof satisfactory polyesters include poly(trans-1,4-cyclohexylene C 2-6alkane dicarboxylates such as poly(trans-1,4-cyclohexylene succinate)and poly(trans-1,4-cyclohexylene adipate), poly(cis ortrans-1,4-cyclohexanedimethylene) C 0-2 alkanedicarboxylates such aspoly(cis 1,4-cyclohexane-di-methylene)oxalate and poly-(cis1,4-cyclohexane-di-methylene) succinate, poly(C 2-4 alkyleneterephthalates) such as polyethyleneterephthalate andpolytetramethylene-terephthalate, poly(C 2-4 alkylene terephthalates)such as polyethyleneterephthalate and polytetramethylene-terephthalate,poly(C 2-4 alkylene isophthalates such as polyethyleneisophthalate andpolytetramethylene-isophthalate, poly(p-phenylene C 1-3alkanedicarboxylates such as poly(p-phenylene glutarate) andpoly(p-phenylene adipate), poly(p-xylene oxalate), poly(oxyleneoxalate), poly(p-phenylenedi-C 1-5 alkylene terephthalates) such aspoly(p-phenylenedimethylene terephthalate) andpoly(p-phenylene-di-1,4-butylene terephthalate, poly-(C 2-10 alkylene1,2-ethylenedioxy-4,4-dibenzoates) such aspoly(ethylene-1,2-ethylenedioxy-4,4-dibenzoates),poly-(tetramethylene-1,2-ethylenedioxy-4,4-dibenzoate) andpoly-(hexamethylene-1,2-ethylene-dioxy-4,4-dibenzoate), poly(C 3-10alkylene-4,4-dibenzoates) such as poly(pentamethylene-4,4-dibenzoate),poly(hexamethylene-4,4-dibenzoate andpoly(decamethylene-4,4-dibenzoate), poly(C 2-10 alkylene-2,6-naphthalenedicarboxylates) such as poly-(ethylene-2,6-naphthalene dicarboxylates)poly(trimethylene-26-naphthalene dicarboxylates) andpoly(tetramethylene-2,6-naphthalene dicarboxylates), and poly-(C 2-10alkylene sulfonyl-4,4-dibenzoates) such as poly(octamethylenesulfonyl-4,4-dibenzoate) and poly(decamethylene sulfonyl-4,4-dibenzoate.

[0016] Additional examples of satisfactory linear polyesters aredescribed in 11 ENCYCLOPEDIA OF POLYMER SCIENCE AND TECHNOLOGY 68-73(John Wiley & Sons 1969) and Korshak & Vinogradova, POLYESTERS 31-64(Pergamon Press). Suitable polycarbonates are also commerciallyavailable. Polylactones such as polycaprolactone are satisfactory in thepractice of the invention. Preferred polyesters of the invention arederived from aromatic dicarboxylic acids such as naphthalenic orphthalic acids. More preferred polyesters are poly(alkyleneterephthalates) especially polytetramethylene terephthalate), or mixedpolyphthalates derived from two or more glycols, two or more phthalicacids, or two or more glycols and two or more phthalic acids such aspoly(alkylene terecoisophthalates).

[0017] Suitable chloromethylated(styrene-isobutylene) polymers for useas a component of the composition of the present invention comprise from1 to a 30 mole percent styrene, preferably from 1 to 20 mole percentstyrene, and most preferably from 1 to 10 mole percent styrene.Preferably these polymers contain from 0.5 to 10 mole percentchloromethylated styrene, more preferably from 0.5 to 5 mole percentchloromethylated styrene, and most preferably from 0.5 to 2 mole percentchloromethylated styrene.

[0018] Stated another way, suitablechloromethylated(styrene-isobutylene) polymers for use as a component ofthe composition of the present invention comprise at least 0.5 wt % ofthe chloromethylated styrene moiety (either para or meta isomers) byweight of the polymer, preferably from 1 wt % to 60 wt %, morepreferably from 1 to 40 wt %, even more preferably from 2 to 20 wt % ofthe polymer. The chlorine content of the polymers may range from abovezero to 10 wt %, preferably from 0.1 to 7 wt %.

[0019] Various methods may be used to produce thechloromethylated(styrene-isobutylene) polymers. Specific methods aredescribed in U.S. Pat. Nos. 3,948,868, 4,074,035 and 5,629,386.Preferably the polymer is prepared such that it is homogeneous. Methodsfor preparing such homogenous (i.e., essentially free of homopolymer)polymers are described in U.S. Pat. No. 3,948,868. Generally this methodinvolves modifying the process such that essentially equal reactivityratios are achieved for styrene and isobutylene. The polymer, or“tetramer”, is prepared by contacting under suitable polymerizationconditions isobutylene monomers, styrene monomers, and a halomethylatingagent, thus generating a random copolymer or tetramer having fourdifferent monomer-derived units: the isobutylene derived units, thestyrene derived units, and both meta- and para-halomethylated-styreneunits.

[0020] More specifically, in one embodiment of the invention, thechloromethylated(styrene-isobutylene) polymer is a chloromethylated“tetramer” of four distinct monomers: isobutylene, styrene,p-(chloromethyl)styrene, and m-(chloromethyl)styrene. A representativestructure of this tetramer is shown below below:

[0021] wherein the subscript “n”, “n”′, and “n”″ represent the number ofisobutylene derived units in a tetramer chain and can be the same ordifferent, “O” represents the number of styrene derived units in thetetramer chain, “P” represents the number of p-(chloromethyl)styrenederived units in the tetramer chain, and “Q” represents the number ofm-(chloromethyl)styrene derived units in the tetramer chain. Thechloromethylated(styrene-isobutylene) tetramer of the invention is arandom polymer of the four units described above, and it is understoodthat the above structure is merely descriptive of the tetramer. In oneembodiment of the chloromethylated(styrene-isobutylene) tetramer, thechloromethylated styrenic units are a heterogeneous mixture such thatthe ratio of the para to meta isomer may vary.

[0022] In the compositions of the present invention, the thermoplasticresin(s) may suitably be present in an amount ranging from 10 to 98 wt%, preferably from 20 to 95 wt %, thechloromethylated(styrene-isobutylene) polymer may be present in anamount ranging from 2 to 90 wt %, preferably from 5 to 80 wt %, based onthe polymer blend.

[0023] The secant flexural modulus of the thermoplastic compositions mayrange from 100 kg/cm² to 400,000 kg/cm² preferably from 200 kg/cm² to100,000 kg/cm² measured according to ASTM D790 at 1% strain.

[0024] The polymer blend may comprise 25 to 98 wt %. Percent of theoverall composition. In addition to its polymer components, thecomposition of the present invention may comprise fillers, and additivessuch as antioxidants, stabilizers, rubber processing oils lubricants(e.g., oleamide), antiblocking agents, waxes, foaming agents, flameretardants, pigments, coupling agents for the fillers and otherprocessing aids known to the rubber compounding art. Metal oxides, e.g.,MgO, can be included to act as acid acceptors. The pigments and fillersmay comprise up to 30 wt %. Percent of the total composition based onpolymer components plus additives. Preferably, the pigments and fillerscomprise 1 to 30 wt %. Percent based on the composition, more preferably2 to 20 wt % of the overall composition.

[0025] Suitable fillers include talc, calcium carbonate, glass fibers,clays, silica, carbon black and mixtures thereof. Any type of carbonblack can be used, such as channel blacks, furnace blacks, thermalblacks, acetylene black, lamp black and the like. Titanium dioxide, alsoconsidered a pigment, can be used to impart a white color to the finalproduct.

[0026] Rubber process oils have particular ASTM designations dependingon whether they fall into the class of paraffinic, naphthenic oraromatic process oils. The type of process oil utilized will be thatcustomarily used in conjunction with the rubber component. The skilledrubber chemist will recognize which type of oil should be utilized witha particular rubber. The quantity of rubber process oil utilized isbased on the total rubber content, and can be defined as the ratio, byweight, of process oil to the rubber in the composition. This ratio canvary from 0.3/1 to 1.3/1; preferably 0.5/1 to 1.2/1; more preferably0.8/1 to 1.1/1. Oils other than petroleum based oils such as oilsderived from coal tar and pine tar can also be utilized. In addition tothe petroleum-derived rubber process oils, organic esters and othersynthetic plasticizers can be used. As used herein, the term “processoil” means both the petroleum derived process oils and syntheticplasticizers.

[0027] The process oil may be included in the composition to insure thatthe composition has good flow properties. The quantity of oil utilizedwill depend in part on the amount of polymer blend and filler used aswell as, to some extent, the type of cure system utilized. Generally,the process oil, when included, may comprise 30 wt. Percent of thecomposition. Larger amounts of process oil can be used, the deficitbeing reduced physical strength.

[0028] Antioxidants may be utilized in the composition of this inventionto enhance further the improved aging properties of the elastomericpolymer component of the present invention and to protect the resins.The particular antioxidant utilized will depend on the rubbers andplastics utilized and more than one type may be required. Their properselection is well within the skill of the rubber chemist. Antioxidantswill generally fall into the class of chemical protectors or physicalprotectants. Physical protectants are used where there is to be littlemovement in the part to be manufactured from the composition. These aregenerally waxy materials which impart a “bloom” to the surface of therubber part and form a protective coating or shield the part fromoxygen, ozone, etc.

[0029] The chemical protectors generally fall into three chemicalgroups: secondary amines, phenolics and phosphites. Illustrative,non-limiting examples of types of antioxidants useful in the practice ofthis invention are hindered phenols, amino phenols, hydroquinones,alkyldiamines, amine condensation products, etc. Nonlimiting examples ofthese and other types of antioxidants are styrenated phenol;2,2′-methylene-bis-(4-methyl-6-1, butylphenol);2,6′-di-t-butyl-o-dimethylamino-p-cresol; hydroquinone monobenzyl ether,octylated diphenylamine, phenyl-beta-naphthlylamine;N,N′-diphenylethylene diamine; aldol-alpha-naphthylamine;N,N′-di-phenyl-p-phenylene diamine, etc. The physical antioxidantsinclude mixed petroleum waxes and microcrystalline waxes.

[0030] It is within the scope of this invention to incorporate anuncured rubber in combination with a dynamically vulcanized rubber inthe composition. This can be accomplished by selecting as the uncuredrubber a rubber which cannot be vulcanized by the vulcanizing agent usedto cure the chloromethylated(styrene-isobutylene) polymer component ofthe present invention which is to be dynamically vulcanized or by addingto the dynamically vulcanized thermoplastic composition, after thevulcanization agent has been fully consumed, a rubber which isvulcanizable by the vulcanization agent used to vulcanize thechloromethylated(styrene-isobutylene) polymer component of the presentinvention. For example, when the chloromethylated(styrene-isobutylene)polymer component of the present invention is vulcanized with a curesystem which comprises zinc oxide, any other rubber which requiressulfur or another curative to vulcanize it or which is not vulcanizablecan be included. Such rubbers include ethylene-propylene polymers (EPM),ethylene-propylene-diene polymers (EPDM), butyl rubbers, halogenatedbutyl rubbers, natural rubber, etc. Alternatively, the DVA can beprepared first from the resin and vulcanizable elastomer by dynamicvulcanization and subsequently, an uncured rubber can be blended intothe DVA at a temperature above the melting point of the thermoplasticresin. In the embodiment in which an uncured rubber is incorporated inthe dynamically vulcanized composition, the uncured rubber may bepresent in an amount ranging from above zero to 25, preferably from 5 to20 wt % of the total rubber (i.e., elastomer) content of thecomposition.

[0031] When it is desired to produce a vulcanized composition, anyconventional curative system which is capable of vulcanizing saturatedhalogenated polymers may be used to vulcanize at least thechloromethylated(styrene-isobutylene) polymer, except that peroxidecuratives should be avoided when the thermoplastic resins chosen ascomponents are such that peroxide would cause these thermoplastic resinsthemselves to crosslink.

[0032] Furthermore, any curative which would cause the particular resinbeing used to crosslink under the processing conditions being used toprepare the dynamically vulcanized alloy should be excluded from thecurative system used. Suitable curative systems for thechloromethylated(styrene-isobutylene) polymer component of the presentinvention include zinc oxide in combination with zinc stearate orstearic acid and, optionally, one or more of the following acceleratorsor vulcanizing agents: Permalux (di-ortho-tolylguanidine salt ofdicatechol borate), HVA-2 (m-phenylene bis maleimide), Zisnet(2,4,6-trimercapto-5-triazine), ZDEDC (zinc diethyl dithiocarbamate) andother dithiocarbamates, Tetrone A (dipenta-methylene thiuramhexasulfide), Vultac-5 (alkylated phenol disulfide), SP1045 (phenolformaldehyde resin), SP1056 (brominated alkyl phenol formaldehyderesin), DPPD (diphenyl phenylene diamine), salicyclic acid (o-hydroxybenzoic acid), wood rosin (abietic acid), and TMTDS (tetramethyl thiuramdisulfide) in combination with sulfur. The vulcanization is conducted atconditions to vulcanize at least partially, preferably fully, thechloromethylated(styrene-isobutylene) polymer.

[0033] In the practice of this invention, the resin, thechloromethylated(styrene-isobutylene) polymer and optional otherpolymers and/or additives are mixed together at a temperature sufficientto soften the resin or, more commonly, at a temperature above itsmelting point when the resin is crystalline at room temperature. If themixture is to be dynamically vulcanized, after the resin and otherpolymers have been intimately mixed, the curative or curatives areadded. Heating and masticating at vulcanization temperatures aregenerally adequate to complete vulcanization in 0.5 to 10 minutes. Thevulcanization time can be reduced by elevating the temperature ofvulcanization. A suitable range of vulcanization temperatures is fromthe melting point of the matrix resin to 300° C.; more typically, thetemperature may range from the melting point of the matrix resin to 275°C. Preferably the vulcanization is carried out at a temperature rangefrom the flux temperature of the polymer blend to 20° C. above thesoftening or melting temperature of the matrix resin.

[0034] It is preferred that the mixing process be continued until thedesired level of vulcanization is completed. If vulcanization ispermitted to continue after mixing has stopped, the composition may notbe reprocessable as a thermoplastic. However, the dynamic vulcanizationcan be carried out in stages. For example, vulcanization can becommenced in a twin screw extruder and pellets formed of the DVAmaterial using an underwater pelletizer thereby quenching thevulcanization before it is completed. It can be completed at a latertime under dynamic vulcanization conditions. Those skilled in the artwill appreciate the appropriate quantities, types of curatives andextent of mixing time required to carry out the vulcanization of therubber. Where necessary the rubber alone can be vulcanized using varyingamounts of curative to determine the optimum cure system to be utilizedand the appropriate cure conditions to achieve a full cure.

[0035] While it is preferred that all components be present in the mixprior to carrying out the dynamic vulcanization process of thisinvention, this is not a necessary condition. For example, in oneembodiment, the chloromethylated(styrene-isobutylene) polymer to becured can be dynamically vulcanized in the presence of a portion or allof the resin. This blend can then be let down into additional resin.Similarly, it is not necessary to add all of the fillers and oil priorto dynamic vulcanization. A portion or all of the additives, fillers andoil can be added during or after the vulcanization is completed. Certainingredients, such as stabilizers and process aids function moreeffectively if they are added after curing.

[0036] The term “rubber” is used herein interchangeably with“elastomer.” The term “fully vulcanized” as used herein with respect tothe dynamically vulcanized rubber components of this invention meansthat the rubber components to be vulcanized have been cured to a statein which the physical properties of the rubber are developed to impartelastomeric properties to the rubber generally associated with therubbers in their conventionally vulcanized state. The degree of cure ofthe vulcanized rubber can be described in terms of gel content orconversely extractable components. Alternatively, the degree of cure canbe expressed in terms of cross-link density.

[0037] Where the determination of extractables is an appropriate measureof the state of cure, the improved thermoplastic elastomericcompositions are produced by vulcanizing the curable rubber componentsof the blends to the extent that they contain no more than four percentby weight of the cured rubber components extractable at room temperatureby a solvent which dissolves the rubbers which are intended to bevulcanized, and preferably to the extent that the composition containsless than two percent by weight extractable. In general, the lessextractables of the cured rubber components, the better are theproperties and still more preferable are compositions comprisingessentially no extractable rubber from the cured rubber phase (less than0.5 wt %). Gel content reported as percent gel is determined by aprocedure which comprises determining the amount of insoluble polymer bysoaking the specimen for 48 hours in organic solvent at room temperatureand weighing the dried residue and making suitable corrections basedupon knowledge of the composition. Thus, corrected initial and finalweights are obtained by subtracting from the initial weight, the weightof soluble components, other than the rubber to be vulcanized, such asextender oils, plasticizers and components of the composition soluble inorganic solvent as well as that of any rubber component, if optionallypresent, of the DVA which is not intended to be cured. Any insolublepigments, fillers, etc., are subtracted from both the initial and finalweights.

[0038] To employ cross-link density as the measure of the state of curewhich characterizes the improved thermoplastic elastomeric compositions,the blends are vulcanized to the extent which corresponds to vulcanizingthe same rubber as in the blend statically cured under pressure in amold with such amounts of the same curatives as in the blend and undersuch conditions of time and temperature to give an effective cross-linkdensity greater than 3×10⁻⁵ moles per milliliter of rubber andpreferably greater than 5×10⁻⁵ or even more preferably 1×10⁻⁴ moles permilliliter of rubber. The blend is then dynamically vulcanized undersimilar conditions with the same amount of curative based on the rubbercontent of the blend as was required for the rubber alone. Thecross-link density so determined may be regarded as a measure of theamount of vulcanization which gives the improved thermoplastics.However, it should not be assumed from the fact that the amount ofcurative is based on the rubber content of the blend and is that amountwhich gives the rubber alone the its cross-link density, that thecurative does not react with the resin or that there is no reactionbetween the resin and rubber. There may be highly significant reactionsinvolved but of limited extent. However, the assumption that thecrosslink density determined as described provides a usefulapproximation of the cross-link density of the thermoplastic elastomericcompositions is consistent with the thermoplastic properties and withthe fact that a large proportion of the resin can be removed from thecomposition by high temperature solvent extraction, with an appropriatesolvent for the resin being used.

[0039] The cross-link density of the rubber is determined by equilibriumsolvent swelling using the Flory-Rehner equation, as shown in 30 J.RUBBER CHEM. & TECH. 929. The appropriate Huggins solubility parametersfor rubber solvent pairs used in the calculation were obtained from thereview article by Sheehan and Bisio, 39 RUBBER CHEM. & TECH. 149-192(1966). If the extracted gel content of the vulcanized rubber is low, itis necessary to use the correction of Bueche wherein the term v ismultiplied by the gel fraction (% gel/100). The cross-link density ishalf the effective network chain density v determined in the absence ofresin. The cross-link density of the vulcanized blends will, therefore,be hereinafter understood to refer to the value determined on the samerubber as in the blend in the manner described. Still more preferredcompositions meet both of the aforedescribed measures of state of cure,namely, by estimation of cross-link density and percent of rubberextractable.

[0040] The thermoplastic resin and chloromethylated(styrene-isobutylene)polymer may also be blended according to the methods disclosed in EP 969039A1 which results in a fine dispersion of thechloromethylated(styrene-isobutylene) polymer within thermoplastic resinmatrix.

INDUSTRIAL APPLICABILITY

[0041] It has been found that blendingchloromethylated(styrene-isobutylene) tetramer with a thermoplasticresin selected from the group consisting of polyamides, polyesters,polycarbonates, polysulfones, polyacetals, polyacetones,acrylonitrile-butadiene styrene resins, polyphenylene oxide,polyphenylene sulfide, styrene-acrylonitrile resins, styrene-maleicanhydride resins, polyamides, aromatic polyketones, ethylene vinylalcohol polymer and mixtures thereof, produces a thermoplastic elastomercomposition with improved durability and gas permeation. By molding thethermoplastic elastomer composition obtained into a sheet, film, or tubeusing a T-sheeting die, straight or crosshead structure tubing die,inflation molding cylindrical die, etc. at the end of the single-screwextruder, it is possible to use the resin as an innerliner or the airpermeation preventive layer of the pneumatic tire and the rubber/resinlaminate of a hose etc.

[0042] While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to many differentvariations not illustrated herein. For these reasons, then, referenceshould be made solely to the appended claims for purposes of determiningthe true scope of the present invention.

[0043] All priority documents are herein fully incorporated by referencefor all jurisdictions in which such incorporation is permitted. Further,all documents cited herein, including testing procedures, are hereinfully incorporated by reference for all jurisdictions in which suchincorporation is permitted.

1. A composition comprising a blend of chloromethylated(styrene-isobutylene) tetramer and a thermoplastic resin selected fromthe group consisting of polyamides, polyesters, polycarbonates,polysulfones, polyacetals, polyacetones, acrylonitrile-butadiene styreneresins, polyphenylene oxide, polyphenylene sulfide,styrene-acrylonitrile resins, styrene-maleic anhydride resins, aromaticpolyketones, ethylene vinyl alcohol polymer and mixtures thereof.
 2. Thecomposition of claim 1, wherein the tetramer is comprised of isobutylenederived units, styrene derived units, p-(chloromethyl)styrene derivedunits, and p-(chloromethyl)styrene derived units.
 3. The composition ofclaim 2, wherein the chloromethylated derived units comprise greaterthan 0.5 wt % of the tetramer.
 4. The composition of claim 1, whereinthe composition is a non-vulcanized composition.
 5. The composition ofclaim 1, wherein the composition is a vulcanized composition.
 6. Thecomposition of claim 5, wherein the vulcanized composition is adynamically vulcanized composition.
 7. The composition of claim 3,wherein the chloromethylated(styrene-isobutylene) polymer is at leastpartially vulcanized.
 8. The composition of claim 3, wherein thechloromethylated(styrene-isobutylene) polymer is at least 90%vulcanized.
 9. The composition of claim 1, wherein the resin is presentin an amount ranging from 10 to 98 wt %, and thechloromethylated(styrene-isobutylene) polymer is present in an amountranging from 2 to 90 wt %, based on the polymer blend.
 10. Thecomposition of claim 1, wherein the resin is present in an amountranging from 20 to 95 wt %, and thechloromethylated(styrene-isobutylene) polymer is present in an amountranging from 5 to 80 wt %, based on the polymer blend.
 11. Thecomposition of claim 1, wherein thechloromethylated(styrene-isobutylene) polymer is present in thecomposition as particles dispersed in the resin.
 12. The composition ofclaim 1, wherein the resin comprises a polyamide.
 13. The composition ofclaim 10, wherein the polyamide is selected from the group consisting ofNylon 6, Nylon 6,6; Nylon 6/66 polymer, Nylon 11 and mixtures thereof.14. The composition of claim 1, wherein thechloromethylated(styrene-isobutylene) polymer comprises from above zeroto 10 wt % chlorine.
 15. The composition of claim 1, wherein thechloromethylated(styrene-isobutylene) polymer comprises from 1 to 30mole percent styrene.
 16. The composition of claim 1, wherein thechloromethylated(styrene-isobutylene) polymer comprises from 0.5 to 10mole percent chloromethylated styrene.
 17. The thermoplastic compositionof claim 1, additionally comprising a component selected from the groupconsisting of a filler, a rubber compounding additive, and mixturesthereof.
 18. The thermoplastic composition of claim 1, additionallycomprising a component selected from the group consisting of rubberprocessing oils, plasticizers, and mixtures thereof.
 19. Thethermoplastic composition of claim 1, the composition has a secantflexural modulus ranging from 100 to 400,000 kg/cm² measured accordingto ASTMD 790 at 1% strain.
 20. A composition comprising a blend ofchloromethylated(styrene-isobutylene) tetramer and a thermoplastic resinselected from the group consisting of polyamides, ethylene vinyl alcoholpolymer and mixtures thereof, wherein thechloromethylated(styrene-isobutylene) polymer comprises from 1 to 30mole percent styrene and from 0.5 to 10 mole percent chloromethylatedstyrene.
 21. A composition comprising a blend ofchloromethylated(styrene-isobutylene) tetramer and a polyamide resinselected from the group consisting of polycaprolactam (Nylon-6),polylauryllactam (Nylon-12), polyhexamethyleneadipamide (Nylon-6,6),poly-hexamethyleneazelamide (Nylon-6,9), polyhexamethylenesebacamide(Nylon-6, 10), polyhexamethyleneisophthalamide (Nylon-6,IP), thecondensation product of 11-amino-undecanoic acid (Nylon-11), Nylon 6(N6), Nylon 11 (N11), Nylon 12 (N12), a Nylon 6/66 polymer (N6/66),Nylon 610 (N610), Nylon 612 (N612), and mixtures thereof.
 22. A tirecomprising the thermoplastic composition of claim
 1. 23. A tirecomprising the thermoplastic composition of claim
 20. 24. A tirecomprising the thermoplastic composition of claim
 21. 25. An airpermeation prevention film, the film comprising the thermoplasticcomposition of claim
 1. 26. An air permeation prevention film, the filmcomprising the thermoplastic composition of claim
 20. 27. An airpermeation prevention film, the film comprising the thermoplasticcomposition of claim
 21. 28. A tire innerliner comprising thethermoplastic composition of claim
 1. 29. A tire innerliner comprisingthe thermoplastic composition of claim
 20. 30. A tire innerlinercomprising the thermoplastic composition of claim
 21. 31. Thecomposition of claim 21, wherein the tetramer is comprised ofisobutylene derived units, styrene derived units,p-(chloromethyl)styrene derived units, and p-(chloromethyl)styrenederived units.
 32. The composition of claim 31, wherein thechloromethylated derived units comprise greater than 0.5 wt % of thetetramer.
 33. The composition of claim 20, wherein thechloromethylated(styrene-isobutylene) tetramer is a random polymer.